Process and apparatus for texturizing yarn

ABSTRACT

A method and device for crimping continuous filament yarn comprising providing a gas-actuated aspirator tube which serves to pull the yarn from its source and direct it to a crimping region which comprises a diffuser means downstream from the aspirator which separates the gas from the yarn, crimps the yarn and serves as a pressure means for forcing the yarn into a heater region where the crimping is set.

United States Patent Inventor William D. Porter Asheville, N.C.

Appl. No. 848,875

Filed Aug. 11, 1969 Patented July 27, 1971 Assignee Northrop Carolina,lnc.

Swannanoa, N.C.

PROCESS AND APPARATUS FOR TEXTURIZING YARN 13 Claims, 1 Drawing Fig.

US. Cl 28/1.3, 28172.1 1

Int. Cl D02g l/OO FieldofSearch ..28/1.3, 1.4,

[56] References Cited UNITED STATES PATENTS 3,256,582 6/1966 Burleson28/1.3 3,296,677 1/1967 Chase 28/1.3 3,303,546 2/1967 Van Blerk 28/l.33,343,240 9/1967 Parmeggiani et al. 28/1 .3 3,373,470 3/1968 Joly28/72.11 3,409,956 1 H1968 Longbottorn et a1. 28/1.3

Primary Examiner-Louis K. Rimrodt AttorneysSokolski and Wohlgemuth andW. M, Graham ABSTRACT: A method and device for crimping continuousfilament yarn comprising providing a gas-actuated aspirator tube whichserves to pull the yarn from its source and direct it to a crimpingregion which comprises a diffuser means downstream from the aspiratorwhich separates the gas from the yarn, crimps the yarn and serves as apressure means for forcing the yarn into a heater region where thecrimping is set.

lllllll l' Q a PAIENTED JUL2 1 an R. m R ND. WM mm L M w SOKOLSK/ 8WOHLGE MU TH PNEUMATIC VIBRA TOR PROCESS AND APPARATUS FOR TEXTURlZlNGYARN Considerable technology and prior patented art exist in the fieldof crimping of filaments of synthetic fibers such as rayon, nylon,acetate, acrylate, polyesters and the like. Generally the crimping ofthese fibers is accomplished by mechanically stuffing them into a tubeor other suitable container whereupon they fold upon themselves underthe pressure of the feeding action. While in the container, and in afolded form, they are heated to permanently set the crimp. The previoustechnology has dealt with the problems of obtaining a proper residencetime for the filaments during the heat setting thereof. In order toproduce a suitable product the fibers should all be subjected toessentially the same residence time in the heated region where they havebeen stuffed and crimped.

In most all of the prior devices, the yarn is fed to the stuffingchamber by a pair of feed rollers with various mechanical andelectromechanical means for controlling the rate at which the fibers areintroduced and removed from the chamber. As aresult, complex mechanicaland electrical means have been devised for controlling the rate at whichthe feed rollers feed the fibers to the stuffing chamber and/or themeans by which the fibers are released or taken up from the chamber.Such prior means are not only complex and thus subject to breakdown andrepair, but further they considerably increase the cost of the crimpingoperation.

Thus, an object of this invention is to provide a process and apparatusto simplify the crimping of yarn.

Another object of this invention is to provide a process and apparatushaving few, if any, moving parts to be utilized in crimping yarns.

Still another object of this invention is to provide a process andapparatus for crimping of yarns which is relatively low cost.

Still one other object of this invention is to provide a process andapparatus which can crimp yarns at higher speeds than those utilized onmechanically fed stuffer box crimpers currently in use.

The above and other objects of this invention are accomplished by aprocess and associated apparatus which comprises an aspirator tubedisposed downstream from the storage spool of the yarn to be crimped.The yarn is first directed to an inlet tube whose end is adjacent aninlet of the aspirator. The pressurized gas which is directed throughthe aspirator tube serves to create a vacuum in the inlet through aventuri effect, thus sucking the yarn through the inlet tube. After theyarn passes through the inlet tube, it continues through the aspiratorwhich terminates in a nozzle exit area where a highvelocity stream ofgas further tensions and propels the yarn forward, finally expelling theyarn and the converging gas to a diffuser. The diffuser can, forexample, be a tube having a plurality of perforations in the outer wall.The diffuser is of a diameter and length sufficient to accumulate aconfiguration of packed yarn suitable to developing random or orientedyarn crimps of the desired amplitude and frequency. This is accomplishedby placing an initial blockage at the downstream end of the diffusertube. The holes or perforations in the walls of the diffuser tube allowthe gas to separate from the yarn without allowing yarn blowback orescape. As the diffuser plugs with yarn, and begins to build backwardtoward the aspirator, the holes in its surface are blocked by the yarnplug,

- thus reducing the area through which the gas can escape. This causes apressure buildup in the diffuser. This means for blocking the yarn fromexiting the diffuser is then removed and the plug of yarn remains staticin the diffuser until the diffuser fills and covers sufficient gas exitholes to cause the back pressure to build up to a point where the plugof yarn will be pushed forward from the tube by gas pressure.

Once the process is started, and the blockage means is removed, itbecomes continuous with a steady plug of yarn existing in the diffusertube and moving on from it into a heater region where the yarn is set inthe crimp. The yarn is then directed from the heater to an area whereall heat above ambient is removed. This area of the apparatus serves asa reservoir for accumulated yarn in which a continuous process can takeaway the yarn, accounting for slight variations in crimp level withoutpulling excessive tensions in the yarn or moving the reservoir levelbelow a point where it has been adequately cooled.

In one embodiment of the invention the aspirator section of the devicecan be vibrated so as to randomly position the yarn in a crimped mannerwithin the diffuser tube.

It is believed that the invention will be better understood from thefollowing detailed description and drawing in which:

The FIGURE is a partially cross-sectioned pictorial representation ofthe apparatus of the invention to perform the crimping process.

Turning now to the FIGURE, there is seen a spool of continuous filamentyarn 11. The yarn 13 can be directed to the device 15 of the inventionby means of an idler roller 17 or other suitable guide means, dependingupon the location of the spool relative to the device 15. In addition tofeeding the yarn from a spool, it can be fed directly from a continuousspinning process as well.

The device 15 of the invention includes an end fitting 19. Threadablyinserted in the forward closed end 21 of the fitting 19 is an inlet tube23. lntersecting fitting 19 is an inlet air line 25. Tight fitted "orsecured by other means to the downstream and open end 27 of fitting 19is an aspirator tube 29. The aspirator tube 29 is provided with acentral passageway 31 through which the yarn 13 passes as it comes frominlet tube 23. At the upstream end 33 of the aspirator, the areasurrounding the central passage 31 is milled or formed conically at 35to provide an enlarged inlet opening. Likewise, the downstream end ofthe inlet tube 23 is correspondingly formed at 37 to match the wallportion 35 at the inlet of the aspirator. When the inlet tube 23 isseated as shown in the FIGURE, a concentric convergent inlet nozzle 39is thus formed between the end 37 of the inlet tube in the portion 35 ofthe aspirator.

As can be seen, the inlet 39 is directed downstream. Thus, the airentering from inlet 25 will fill chamber 41 between the inlet tube andthe fitting 19 and then pass through the inlet nozzle 39 in a downstreamdirection, thus resulting in a venturi-type effect. This creates apartial vacuum in the inlet tube 23 serving to draw yarn into thedevice. The center passage 31 slightly diverges from the inlet nozzle 39thus serving to increase the gas velocity. The downstream end of theaspiratorv 29 is provided with a divergent portion 43 formed in thewalls of the aspirator. This serves mainly to adapt the aspirator todiffuser tube 45. Further, the divergence serves to additionallyincrease the velocity of the exit gas and thus to further tension andpropel the yarn 13 forward, expelling it into a diffuser tube 45. I

The diffuser tube 45 may be attached to the aspirator 29, or in theembodiment shown, slightly separated therefrom. The difiuser has adiameter and length sufficient to accumulate a configuration of packedyarn and is suitable for developing random or oriented yarn crimp of thedesiredamplitude and frequency. This is accomplished by causing the yarnto fold spirally or otherwise bend to form a desirable texture geometrywhen eventually heat-set in this shape. In the embodiment shown in thedrawing, a pneumatic vibrator 47 is connected to the aspirator 15. Thevibrator 47 causes the aspirator to vibrate and thus control the pointat which the yarn l3 impinges into the yarn plug 49 located in thediffuser. This, thus, in effect controls thelength of the folds formedby the yarn after it is packed into the plug so alternative to vibratingthe aspirator 15, the diffuser could be vibrated to accomplish the sameresult.

The crimp of yarn can be classified into two broad categories: One is aplanar crimp in which all the bends of the yarn lie in a single plane.The other class is a three-dimensional crimp in which the bends may beeither randomly oriented as to the plane in which they lie, orsymmetrically arranged. Although a pneumatic vibrator is shown attachedto the aspirator, this will not be required in all instances since thereis significant turbulence in the impinging air leaving the exit nozzleportion 43 of the aspirator, which tends to create a random folding orlay down of the yarn being textured. As described, when one planevibration is introduced to either the aspirator or the diffuser, aplanar crimp will most likely result in the yarn. Alternatively, arandom mode of vibration in either of the two elements would produce arandom crimp. Still further variation would, for example, result if thediffuser zone were rotated imparting a spiral or corkscrew yarn texturegeometry. Thus it can be appreciated that significant variations as tothe form and shape of the crimping can be achieved through relativepositioning of the outlet nozzle of the aspirator to the diffuser.

The diffuser 45 is provided with a plurality of smallapertures 51 whichallow the gas to be separated from the yarn in the diffuser. The holesare of sufficiently small diameter that the yarn cannot be blown into orthough them as the gas is separated. Further, the apertures are spacedso that the tube will have sufficient open area to allow all of the gas.to be efficiently separated from the yarn without allowing yarn blowbackor escape.

Downstream from the diffuser 45 is a stuffer tube 53 which receives theplug of yarn 49 from the diffuser. The stuffer tube 53 is surroundedadjacent its upstream portion by heater chamber 55. Hot air or gas iscirculated through the chamber 55 by inlet line 57 and exit line 59.This serves to set the crimp or folds that have been placed in the yarnin a manner conventional in the art. Alternate to the use of gas, ofcourse, a resistant electric heater or the like could be utilized inthis region. The stuffer tube 53 has a smooth and regular insidediameter in order that frictional forces may be uniform along itslength. Further, the length of the heater region of the stuffer tubemust be sufficient to allow the yarn to be heated to a temperature atwhich the crimp will set without degrading the polymer material. Theheat-setting temperatures are well known in the industry and areutilized in various other crimping processes.

After the yarn has been set, it then moves into a portion 61 of thestuffer tube downstream from the heater region 55, which allows the yarnto cool by letting the heat-above ambient temperature be effectivelydissipated. This particular area 61 of the stuffer chamber or tube alsoserves as a reservoir for accumulated yarn from which a continuousprocess can take away the material accounting for slight variations incrimp level, without pulling excessive tension in the yarn or moving thereservoir level below the point where it has been adequately cooled.Thus, for example, the reservoir cooling portion 61 can be as long orlonger than the portion of the tube subjected to the heating.

When the yarn 13 is first introduced into the diffuser tube 45, a meansor mechanism 63 is introduced to momentarily block the exit of the yarnfrom the diffuser. This can be simply accomplished by merely placingone's hand over the downstream end 63 of the stuffer tube 53, or throughthe use of a curved pin 65 as shown in the FIGURE. The pin 65 can beattached to a suitable electromechanical apparatus for moving it whendesired in a manner conventional in the art, or of course could be movedby hand. All that is required is to introduce some type of blockingmeans to prevent the highvelocity yarn from blowing freely and undertension through the entire apparatus.

The instant that the yarn begins to fold and slow down, thehigh-velocity yarn overtaking it will almost instantaneously form a yarnbuildup or plug. After the yarn plug has progressed upstream and intothe diffuser 45, the diffuser holes 51 begin to become blocked. Oncethis begins, the means for interrupting the yarn passage can be removedor the yarn winder takeup device can be started. The plug of yarn thenfurther builds up or remains static in the diffuser until the diffuserfills and covers sufficient gas exit holes to cause a back pressure tobuild up to the point where the plug of yarn yarn plug forward andmaintain a self-regulating pressure. The

exiting yarn leaving the device is continuously moved by a winder at aconstant or nearly constant speed which is matched to the yarn supplyspeed entering the crimping apparatus. Alternatively, the pin 65 couldbe selectively controlled to partially block removal and thus serve tospeed up or slow down the process. Such a device is quite conventionalin the art and is thus not described herein nor forms part of theinventive concept.

The process can utilize a fixed relationship between the yarn input andoutput speeds from the apparatus, with the output speed always beingslower. The reason for this is that the texturizing and bending of theyarn reduces its length from 10 to 50 percent depending upon the processparameters. Naturally, the shortening of the yarn is affected by thetension that is pulled on it between its exit from the device of theinvention and the windup package. The inventory of the yarn in the yarnplug is thus self-compensating, both at its point of impingement and thepoint of removal. The air pressure affects the position of the plug inthe diffuser and the yarn removal tension affects the end of the yarnplug inventory. Various commercially available means are available forso affecting the tension between the device of the invention and thewindup apparatus. These include, for example, friction discs, sn ubberpins, slub catchers, and the like, all well known and utilized.

It shouldbe noted that all of the diffuser holes 51 in the diffuser 45are never covered by yarn. In fact, the yarn removal from the entireapparatus must begin before this happens. Otherwise, the diffuser willno longer separate the gas from the yarn and blockage of the aspiratorzone 29 would occur, resulting in a shutdown of the process due toplugging.

As shown in the FIGURE, the diameter of the diffuser 45 and the diameterof the heater zone or stuffer chamber 53 can be the same. However, itmay be necessary for some of the yarns having high coefficients offriction to make the stuffer chamber or tube 53 slightly larger indiameter than the diffuser 45. Additionally, it might be necessary tooutwardly taper the stuffer tube towards its downstream end 63 to alarger diameter. For example,from,l to 5 of divergence in the stuffertube can serve to reduce the flow of the yarn plug through theapparatus.

In the aforegoing description, air or similar gas is referred to asentering inlet line 25 serving to propel and initially pull the yarninto the device through the aspirator section 29. A further advantage ofthis invention is that the gas temperature can be controlled. Thus, byraising the gas temperature one can preheat the yarn and control andalter its modulus of elasticity. This causes the yarn to filldifferently as it is packed into the diffuser tube. As a result, notonly warm air can be utilized, but steam and the like to serve theaforegoing function of heating the yarn while serving to propel it.

Another variation of the device of the invention could have the exitnozzle portion 43 of the aspirator 29 as a movable rotatable elementwhich could be controlled to rotate or move causing a swirling of theexiting yarn. As a result, the impact of the yarn in the diffuser tubecould be effectively varied in a multitude of patterns.

Thus, it can be seen from the aforegoing description that an essentiallynonmechanical device and resulting process has been disclosed for thecrimping of yarn. The utilization of rotary elements to feed the yarninto the crimping box in the prior art results in various problems asindicated. One problem particularly is that it effectively limits thespeed at which the yarn can be processed. The concept of this inventionis not in any way limited in processing speeds, since the time andtemperature requirements in the heating zone can be achieved merely bymaking a relatively short zone longerv The aspirator, for example, cantransport yarn into the diffuser at speeds as high as 5,000 yards perminute. This speed is generally considerably in excess of that availablein other types of apparatus.

I claim:

l. A device for crimping yarn comprising:

a gas actuated aspirator,

means for directing said yarn to an upstream end of said aspirator,

means downstream from said aspirator for forming a yarn plug andcrimping said yarn therein and,

means cooperating with said aspirator for selectively controlling thepoint at which the yarn leaving the aspirator impinges upon said yarnplug to vary the type of crimp put into the yarn.

2. The device of claim I further comprising:

means for heat-setting the crimped yarn.

3. The device of claim 1 wherein said gas actuated aspirator comprises:

a generally tubular section,

and means for allowing pressurized gas to enter an upstream end of saidsection and exit a downstream end together with said yarn.

4. The device ofclaim 3 further comprising:

an inlet convergent nozzle formed at the upstream end of said tubularsection,- said gas entering said section through said nozzle. 7

5. The device of claim 4 wherein said means for directing said yarn tosaid aspirator comprises:

a hollow tubular member having an inlet upstream end through which theyarn enters and a downstream exit end,

said exit end cooperating with the inlet of said aspirator to form saidinlet convergent nozzle.

6. The device ofclaim 4 further comprising:

an exit divergent nozzle formed in said tubular section.

7. The device of claim 2 wherein said means for heat-setting comprises:

a hollow tubular member disposed downstream from said receiving andcrimping means,

a heating means surrounding an upstream portion of said tubular member,the remaining downstream portion being of sufficient length to allow theheated yarn to cool.

8. The device of claim 3 wherein said means for forming said plug andcrimping said yarn comprises:

a hollow tubular section having a plurality of apertures in the wallsthereof.

'9. The device of claim 8 wherein said plug-forming and crimping meansis disposed immediately adjacent the exit nozzle of said aspirator.

10. A method of crimping yarn comprising:

directing said yarn to a gas-actuated aspirator,

feeding pressurized gas through said aspirator whereby said yarn ispulled therethrough by the aspirating efi'ect,

selectively folding said yarn into a yarn plug formation to vary thetype of crimp formed in the yarn, and crimping said yarn while in saidplug formation.

11. The method of claim 10 further comprising:

separating the gas leaving the aspirator from the yarn simultaneouslywith the crimping thereof.

12. The method of claim 11 further comprising:

controlling the separation of said gas from said yarn to allow apressure buildup within the crimped yarn plug.

13. The method of claim 10 further comprising:

heating said yarn plug to set the crimp therein, and cooling said heatedyarn

2. The device of claim 1 further comprising: means for heat-setting thecrimped yarn.
 3. The device of claim 1 wherein said gas actuatedaspirator comprises: a generally tubular section, and means for allowingpressurized gas to enter an upstream end of said section and exit adownstream end together with said yarn.
 4. The device of claim 3 furthercomprising: an inlet convergent nozzle formed at the upstream end ofsaid tubular section, said gas entering said section through saidnozzle.
 5. The device of claim 4 wherein said means for directing saidyarn to said aspirator comprises: a hollow tubular member having aninlet upstream end through which the yarn enters and a downstream exitend, said exit end cooperating with the inlet of said aspirator to formsaid inlet convergent nozzle.
 6. The device of claim 4 furthercomprising: an exit divergent nozzle formed in said tubular section. 7.The device of claim 2 wherein said means for heat-setting comprises: ahollow tubular member disposed downstream from said receiving andcrimping means, a heating means surrounding an upstream portion of saidtubular member, the remaining downstream portion being of sufficientlength to allow the heated yarn to cool.
 8. The device of claim 3wherein said means for forming said plug and crimping said yarncomprises: a hollow tubular section having a plurality of apertures inthe walls thereof.
 9. The device of claim 8 wherein said plug-formingand crimping means is disposed immediately adjacent the exit nozzle ofsaid aspirator.
 10. A method of crimping yarn comprising: directing saidyarn to a gas-actuated aspirator, feeding pressurized gas through saidaspirator whereby said yarn is pulled therethrough by the aspiratingeffect, selectively folding said yarn into a yarn plug formation to varythe type of crimp formed in the yarn, and crimping said yarn while insaid plug formation.
 11. The method of claim 10 further comprising:separating the gas leaving the aspirator from the yarn simultaneouslywith the crimping thereof.
 12. The method of claim 11 furthercomprising: controlling the separation of said gas from said yarn toallow a pressure buildup within the crimped yarn plug.
 13. The method ofclaim 10 further comprising: heating said yarn plug to set the crimptherein, and cooling said heated yarn.